One feels the insignificance of the individual, and it makes one happy.

In the matter of physics, the first lessons should contain nothing but what is experimental and interesting to see. A pretty experiment is in itself often more valuable than twenty formulae extracted from our minds.

The supreme task of the physicist is to arrive at those universal elementary laws from which the cosmos can be built up by pure deduction. There is no logical path to these laws; only intuition, resting on sympathetic understanding of experience, can reach them.

I am not only a pacifist but a militant pacifist. I am willing to fight for peace. Nothing will end war unless the people themselves refuse to go to war.

The bigotry of the nonbeliever is for me nearly as funny as the bigotry of the believer.

All means prove but blunt instruments, if they have not behind them a living spirit.

All such action would cease if those powerful elemental forces were to cease stirring within us.